Speaking at the Online Publishers Association's (OPA) forum in London, Emily Bell said in spite of the title's ambitions in the US the monthly figure for UK unique users of the site was critical.
The UK visitors - who accounted for 7,731,573 of Guardian.co.uk's total of 18,703,811 unique users in last month's Audit Bureau of Circulations Electronic (ABCe) report - will continue to be the most important statistic for its advertisers, said Bell.
"It will be several years before the [advertising] networks recognise that we are looking to serve the same kind of audiences internationally," she said.
Her comments today echoed remarks made to Journalism.co.uk earlier this month in which she said it would be a 'natural' progression to expand Comment is Free internationally.
"The Guardian is undoubtedly a British brand at the moment. Our intention is to be an international brand," said Bell.
"The subjects we address and the way we address them are of global concern to a liberal audience."
The Guardian's advertising partnership with Reuters on its US site 'will make a big difference' to its US expansion, Bell added.
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